/**
 * Copyright (c) 2005-2010 springside.org.cn
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * 
 * $Id: ReflectionUtils.java 1211 2010-09-10 16:20:45Z calvinxiu $
 */
package com.alter.utils.reflection;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;

import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.util.Assert;

/**
 * 反射工具类.
 * 
 * 提供访问私有变量,获取泛型类型Class, 提取集合中元素的属性, 转换字符串到对象等Util函数.
 * 
 * @author calvin
 */
public class ReflectionUtils {

    private static Logger logger = LoggerFactory.getLogger(ReflectionUtils.class);

    /**
     * 调用Getter方法.
     */
    public static Object invokeGetterMethod(Object obj, String propertyName) {
	String getterMethodName = "get" + StringUtils.capitalize(propertyName);
	return invokeMethod(obj, getterMethodName, new Class[] {}, new Object[] {});
    }

    /**
     * 调用Setter方法.使用value的Class来查找Setter方法.
     */
    public static void invokeSetterMethod(Object obj, String propertyName, Object value) {
	invokeSetterMethod(obj, propertyName, value, null);
    }

    /**
     * 调用Setter方法.
     * 
     * @param propertyType
     *            用于查找Setter方法,为空时使用value的Class替代.
     */
    public static void invokeSetterMethod(Object obj, String propertyName, Object value, Class<?> propertyType) {
	Class<?> type = propertyType != null ? propertyType : value.getClass();
	String setterMethodName = "set" + StringUtils.capitalize(propertyName);
	invokeMethod(obj, setterMethodName, new Class[] { type }, new Object[] { value });
    }

    /**
     * 直接读取对象属性值, 无视private/protected修饰符, 不经过getter函数.
     */
    public static Object getFieldValue(final Object obj, final String fieldName) {
	Field field = getAccessibleField(obj, fieldName);

	if (field == null) {
	    throw new IllegalArgumentException("Could not find field [" + fieldName + "] on target [" + obj + "]");
	}

	Object result = null;
	try {
	    result = field.get(obj);
	} catch (IllegalAccessException e) {
	    logger.error("不可能抛出的异常{}", e.getMessage());
	}
	return result;
    }

    /**
     * 直接设置对象属性值, 无视private/protected修饰符, 不经过setter函数.
     */
    public static void setFieldValue(final Object obj, final String fieldName, final Object value) {
	Field field = getAccessibleField(obj, fieldName);

	if (field == null) {
	    throw new IllegalArgumentException("Could not find field [" + fieldName + "] on target [" + obj + "]");
	}

	try {
	    field.set(obj, value);
	} catch (IllegalAccessException e) {
	    logger.error("不可能抛出的异常:{}", e.getMessage());
	}
    }

    /**
     * 循环向上转型, 获取对象的DeclaredField, 并强制设置为可访问.
     * 
     * 如向上转型到Object仍无法找到, 返回null.
     */
    public static Field getAccessibleField(final Object obj, final String fieldName) {
	Assert.notNull(obj, "object不能为空");
	Assert.hasText(fieldName, "fieldName");
	for (Class<?> superClass = obj.getClass(); superClass != Object.class; superClass = superClass.getSuperclass()) {
	    try {
		Field field = superClass.getDeclaredField(fieldName);
		field.setAccessible(true);
		return field;
	    } catch (NoSuchFieldException e) {// NOSONAR
		// Field不在当前类定义,继续向上转型
	    }
	}
	return null;
    }

    /**
     * 直接调用对象方法, 无视private/protected修饰符. 用于一次性调用的情况.
     */
    public static Object invokeMethod(final Object obj, final String methodName, final Class<?>[] parameterTypes,
	    final Object[] args) {
	Method method = getAccessibleMethod(obj, methodName, parameterTypes);
	if (method == null) {
	    throw new IllegalArgumentException("Could not find method [" + methodName + "] on target [" + obj + "]");
	}

	try {
	    return method.invoke(obj, args);
	} catch (Exception e) {
	    throw convertReflectionExceptionToUnchecked(e);
	}
    }

    /**
     * 循环向上转型, 获取对象的DeclaredMethod,并强制设置为可访问. 如向上转型到Object仍无法找到, 返回null.
     * 
     * 用于方法需要被多次调用的情况. 先使用本函数先取得Method,然后调用Method.invoke(Object obj, Object...
     * args)
     */
    public static Method getAccessibleMethod(final Object obj, final String methodName, final Class<?>... parameterTypes) {
	Assert.notNull(obj, "object不能为空");

	for (Class<?> superClass = obj.getClass(); superClass != Object.class; superClass = superClass.getSuperclass()) {
	    try {
		Method method = superClass.getDeclaredMethod(methodName, parameterTypes);

		method.setAccessible(true);

		return method;

	    } catch (NoSuchMethodException e) {// NOSONAR
		// Method不在当前类定义,继续向上转型
	    }
	}
	return null;
    }

    /**
     * 通过反射, 获得Class定义中声明的父类的泛型参数的类型. 如无法找到, 返回Object.class. eg. public UserDao
     * extends HibernateDao<User>
     * 
     * @param clazz
     *            The class to introspect
     * @return the first generic declaration, or Object.class if cannot be
     *         determined
     */
    @SuppressWarnings("unchecked")
    public static <T> Class<T> getSuperClassGenricType(final Class clazz) {
	return getSuperClassGenricType(clazz, 0);
    }

    /**
     * 通过反射, 获得Class定义中声明的父类的泛型参数的类型. 如无法找到, 返回Object.class.
     * 
     * 如public UserDao extends HibernateDao<User,Long>
     * 
     * @param clazz
     *            clazz The class to introspect
     * @param index
     *            the Index of the generic ddeclaration,start from 0.
     * @return the index generic declaration, or Object.class if cannot be
     *         determined
     */
    @SuppressWarnings("unchecked")
    public static Class getSuperClassGenricType(final Class clazz, final int index) {

	Type genType = clazz.getGenericSuperclass();

	if (!(genType instanceof ParameterizedType)) {
	    logger.warn(clazz.getSimpleName() + "'s superclass not ParameterizedType");
	    return Object.class;
	}

	Type[] params = ((ParameterizedType) genType).getActualTypeArguments();

	if (index >= params.length || index < 0) {
	    logger.warn("Index: " + index + ", Size of " + clazz.getSimpleName() + "'s Parameterized Type: " + params.length);
	    return Object.class;
	}
	if (!(params[index] instanceof Class)) {
	    logger.warn(clazz.getSimpleName() + " not set the actual class on superclass generic parameter");
	    return Object.class;
	}

	return (Class) params[index];
    }

    /**
     * 将反射时的checked exception转换为unchecked exception.
     */
    public static RuntimeException convertReflectionExceptionToUnchecked(Exception e) {
	if (e instanceof IllegalAccessException || e instanceof IllegalArgumentException || e instanceof NoSuchMethodException) {
	    return new IllegalArgumentException("Reflection Exception.", e);
	} else if (e instanceof InvocationTargetException) {
	    return new RuntimeException("Reflection Exception.", ((InvocationTargetException) e).getTargetException());
	} else if (e instanceof RuntimeException) {
	    return (RuntimeException) e;
	}
	return new RuntimeException("Unexpected Checked Exception.", e);
    }
}
